1. Field of the Invention
The present invention relates to disk brakes for braking vehicles, and more particularly to disk brakes for braking two-wheeled vehicles.
2. Description of the Related Art
In the past, disk brakes for two-wheeled vehicles were constructed as shown in FIGS. 10-12. In the drawings, a U-shaped carrier 1 is fixed to a non-rotation portion (not shown) of a two-wheeled vehicle. A caliper 2 is floatingly supported on the carrier 1. A disk 3 is fixed to an axle hub 4 of the vehicle (FIG. 11). The caliper 2 comprises a cylinder portion 6 including a piston 5, an upper portion 7 extending from the cylinder portion 6 and crossing the disk 3, a claw portion 8 extending radially inwardly of the disk 3 from the upper portion 7, and a pair of arm portions 9 extending in right and left directions from the cylinder portion 6. One of the arm portions 9 is provided at the entrance side of the disk 3 and the other is provided at the exit side thereof. The entrance side arm portion 9 includes a through hole. The exit side arm portion 9 includes a blind hole. The carrier 1 includes support pins 11. One of the support pins 11 extends from the carrier 1 into the through hole of the entrance side arm portion 9. The carrier 1 also includes a bag-shaped flexible bush 10 covering the support pin 11 extending into the through hole of the entrance side arm portion 9. The bush 10 extends outwardly through the through hole of the entrance side arm portion 9. A portion of the bush 10 is attached to the inner wall of the through hole of the entrance side arm portion 9. The through hole of the entrance side arm portion 9 slidably receives the support pin 11 through the bush 10. The blind hole of the exit side arm portion 9 directly slidably receives the support pin 11. Thus the caliper 2 is slidably received on the support pins 11 and is floatingly supported by the carrier 1. Incidentally, 1a designates an attachment hole for mounting the carrier 1 on the vehicle.
The claw portion 8 of the caliper 2 includes a through hole 12 at its proximal and central portion. A pad supporting pin 13 is inserted into the through hole 12. The pin 13 extends from the face of the claw portion 8 through the through hole 12 to a hole 14 provided in the cylinder portion 6, and slidably supports a pair of pads 15 and 16. Each of the pads 15 and 16 comprises a back plate 17 and a lining 18. The lining 18 is integrally molded as one unit and is mounted on the surface of the back plate 17. Each of the back plates 17 includes a through hole 17a. The pin 13 is inserted into the through holes 17a of the back plates 17 and the back plates 17 are slidably supported on the pin 13. The pad 15 is provided close to the piston 5. The piston side pad 15 is supported at one end thereof on the pin 13. The piston side pad 15 is supported at the other end thereof on a step portion 19 (shown in FIG. 10) provided in the carrier 1. The pad 16 is provided close to the claw portion 8. The claw side pad 16 is supported at one end thereof on the pin 13. The claw side pad 16 is supported at the other end thereof on a pin 20 (shown in FIG. 12) mounted on one of the arm portions 9 of the caliper 2. Incidentally, the pin 20 is disposed in coaxial relation to the support pin 11 (shown right and upwardly of FIG. 12).
Pumping oil into the cylinder 6a of the cylinder portion 6 allows the piston 5 to be moved toward the disk 3, thereby permitting the pad 15 to be pressed against one face of the disk 3. In reaction thereto, the caliper 2 is moved relative to the piston 5 so that the pad 16 is pressed against the other face of the disk 3, thereby generating braking power for braking the vehicle. Incidentally, a reference numeral 21 shown in FIG. 11 designates a bleeder for discharging air collected within the cylinder 6a.
The supporting pin 13 includes at the outwardly extending end thereof a flange 22 to be in contact with the claw portion 8. The contact of the flange 22 with the claw portion 8 prevents insertion of the supporting pin 13 into the through hole 12. A clip 23 is mounted on the supporting pin 13 between the claw portion 8 and the back plate 17 of the pad 16, thereby preventing removal of the supporting pin 13 from the through hole 12. The clip 23 is referred as ".beta. clip". As shown in FIG. 12, the clip 23 includes a linear portion 23a to be received in a radially extending hole of the supporting pin 13, and an S-shaped curved portion 23b to be in engagement with the periphery of the supporting pin 13. Fastening the clip 23 to the supporting pin 13 in a snap-clamping connection by the linear portion 23a and the curved portion 23b prevents removal of the clip 23 from the supporting pin 13. Providing the clip 23 in the proximal and central portion of the claw portion 8 of the caliper 2 permits the clip 23 to be covered with the upper portion 7 and the claw portion 8 with the disk brake being mounted on the vehicle, thereby making location of the clip 23 from the outside of the disk brake difficult. This prevents tampering such as removal of the clip 23 and enhances the design of the disk brake in the outward form thereof.
According to the above common disk brake, since space "S" for housing the clip 23 is defined centrally inside of the claw portion 8 of the caliper 2 and the upper portion 7 of the caliper 2 is lengthened more to create the space "S", the size of the upper portion 7 is required to be increased in thickness in order to ensure a desired rigidity of the caliper 2. Thickening the upper portion 7 makes the caliper 2 large and heavy. Therefore, measures have been employed recently in which the mounting position of the supporting pin 13 is changed from the proximal and central portion of the claw portion 8 of the caliper 2 to the side end of the caliper 2 to reduce the thickness of the upper portion 7 without compromising the rigidity of the caliper 2. However, the construction permits the clip 23 for preventing removal of the supporting pin 13 to be easily located from the outside of the caliper 2 so that tampering with, such as by removal of, the clip 23 is possible. Such a construction also lowers the design of the disk brake in the outward form thereof.
In order to remove the drawback, a disk brake employing measures in which the mounting position of the supporting pin 13 is changed to the side end of the caliper 2 include means for fixing the support pin to the caliper in a screw-tightening manner instead of mounting of the support pin on the caliper in the clip-fastening manner. However, to enable screw-tightening, machining is necessary for forming a thread of a screw on the support pin and the caliper, thereby increasing the production costs thereof. In particular, such machining results in losing the merit of the production costs that are brought about by the caliper being integrally molded as one unit.